import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        System.out.println("请输入：");

        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        while (!input.equals("stop")) {
            String s1 = input.toUpperCase();
            String s2 = input.toLowerCase();
            String s3 = s1.concat(s2);
            System.out.println(s1);
            System.out.println(s2);
            System.out.println(s3);
            System.out.println("继续输入（输入stop以结束）：");
            input = scanner.nextLine();

        }
        System.out.println("程序结束！");

        /* // System.out.printf("Hello and welcome!");
        String str = new String("Hello World!");
        String str1 = new String("Tom and Jerry");

        System.out.println(str.toUpperCase());
        System.out.println(str.toLowerCase());
        System.out.println(str.concat(str1));

        // 面向对象的方法
        // 先构造对象，没有对象就没有方法
        String s = new String("abc");
        String s2 = "Def";
        String sr = s.toUpperCase();
        String s2r = s2.toLowerCase();
        String strConcat = sr.concat(s2r);

        System.out.println(s);
        System.out.println(sr);
        System.out.println(s2);
        System.out.println(s2r);
        System.out.println(strConcat); */
    }
}